SW6230804_Design Calculations_20240621 (2)

Project Data Revisions
Project# 2022-046 No Date Description
Project Name Qakridge Duncan
Date 6/20/2024
SAND FILTER WORKSHEET
SCM#1
1) Find the volume of the 1.0"storm using the"Simple Method"(Schueler 1987).
Ca/u/ate%Impervious
Drainage Area= 9.37 acres
Impervious Area= 8.30 acres
Imperv.= 88.58
Calulate Rv
Rv= 0.05+0.9(I)
Rv= runoff coefficient(rato of runoff to ra nI II in inches)
I= percent impervious
Rv= 0.847 in/in
Calculate WQV&WQVadj
WQV=3630 x Rox R,r XA
WQV=volume of runoff gnerated from design Storm
Ro=Design storm= 1 inch
Rv=Runoff Coef= 0.847 inch/inch
A=Drainage Area= 9.37 acre
WQVadj=0.75 z WQV
WQV= 28817 ft3
WQVadj= 21613 ft'
2) Determine filter bed&sedimentation areas with respect to WQV and maximum head
Calculate maximum head on filter Calculate minimum As
Hmaxfilter=WQVadj/As+Af Min As=(240 x Rv x AD)x RD
Hmaxfilter WQVadj As+Af Min As= 1905 ft'
1.5 21613 14409 Design As= 1905 ft`
Chose Af and Ha based on site parameters
Min Af=WQV x Df
kxtx(Ha+Df)
_ WQV=valet quality volume= 28817 cf
_ Df=depth of 1Aer bed= 1 feel
k=coeffoeot ofperm= 3.5 Nday
t= time to drain WQV= 48 hours
Ha average head= 0.84 ft ,�'
Min Af= 2243 ft2
Estimate Hmaxfilter= 1.67 ft Design Af= 19597 fe
based on site consireinis(area or depth)
Surface Area Required= 14409 sf
Surface Area Check= OK
3) Verify Volumes-Calculated Volume must be equal to or greater than WQVadj
Vcalc= As+Af x Hmaxfilter
Vcalc= 35908 ft' -14295
WQVadj= 21613 ft3
Volume Check= OK